If Al Gore's AN INCONVENIENT TRUTH was a restrained, carefully reasoned lecture about the potentially catastrophic effects of global warming, Nadia Conners and Leila Conners Petersen's hugely effective documentary is a terrifying vision of exactly what's in store if we don't pay greater attention to what we're doing to the planet in our blind rush toward "progress." Perhaps this edge is exactly what the movement to reverse climate change needs: If a movie like this doesn’t work, nothing will.

Narrated by Leonardo DiCaprio, who was also a producer, the film opens with flashes of deforestation, squirming embryos, factory-farmed chickens, melting ice shelves and lungs gasping for breath, a startling montage set to the grinding, low-bass doom rock of Khanate. The end is not just nigh, it's well upon us, the film contends, and offers engaging interviews with a host of independent talking heads who are currently on the front lines of the battle to root out the causes and offer possible solutions to ecological and humanitarian disasters. Many will be familiar to anyone who has already seen AN INCONVENIENT TRUTH (2006) or THE GREAT WARMING (2006): Rampant deforestation and fatal reliance on fossil fuel have led to a dangerous buildup of CO2 in our atmosphere resulting in a sharp rise in global temperatures. And we don't have to wait until the polar ice caps melt and flood Florida to witness the disastrous effects: We have only to look at the droughts and severe weather patterns that have devastated Europe, Asia and Africa over the past decade and the aftermath of our own Hurricane Katrina to grasp what lies in store for us. The bottom line should be sobering to anyone who still thinks Al Gore, as one former U.S. president put it, is "nuts": The environment will survive, but it will no longer be one in which we can live. Like countless species before us, we'll become extinct... and we won't be missed.

Where the more frankly political AN INCONVENIENT TRUTH is equally clear about where the blame lies  the petroleum industry, economic globalization, the current U.S. administration  Conners and Conners Petersen are more interested in moving beyond consciousness-raising and looking at some of the solutions suggested by scientists, engineers and environmental designers, many of whom are looking at some of nature's own astonishing feats of engineering and resource reclamation. These solutions are as intriguing as they are inspiring, and in the end may make THE 11TH HOUR the one film to see on this most crucial subject.